In tests on rats, a Royal Veterinary College team fed one group of females a diet of processed junk food such as donuts, muffins, cookies, chips and sweets during pregnancy and breast-feeding, while another group of females received a healthy diet of regular feed.

The researchers compared the offspring of the two groups of female rats and found those born to mothers fed a junk food diet had higher levels of cholesterol and triglycerides, a type of fat found in the bloodstream. Both increase the risk of heart disease.

The offspring of the junk food-fed mothers also had higher levels of glucose and insulin, both of which increase the risk of type 2 diabetes.

These rats remained fatter through adolescence and into adulthood than the offspring of the mothers who ate a healthier diet during pregnancy and breast-feeding.

The study was published in the current issue ofThe Journal of Physiology.

"It seems that a mother's diet whilst pregnant and breast-feeding is very important for the long term health of her child," study co-author Dr. Stephanie Bayol said in a prepared statement. "We always say 'you are what you eat.' In fact, it may be true that 'you are what your mother ate.' This does not mean that obesity and poor health is inevitable, and it is important that we take care of ourselves and live a healthy lifestyle. But it does mean that mothers must eat responsibly whilst pregnant."

Even though this study was carried out in rats, the findings are likely applicable to humans, study co-author Professor Neil Stickland added.

"Humans share a number of fundamental biological systems with rats, so there is good reason to assume the effects we see in rats may be repeated in humans. Our research certainly tallies with epidemiological studies linking children's weight to that of their parents," Stickland said in a prepared statement.